Guys/Gals

I need your help, i am having trouble stopping my Vette from Pinking/pinging at around 2500/3000ish rpm at first i thought the timing was off and i have tried different settings(I have a L82(1976) engine and the book says 12 degrees this didn't seem to be any better, 'someone' has written 8 degrees on the firewall which makes me think someone might have changed the cams ? it does have MT valve covers, but so what!i also discovered the line from the EGR to the inlet manifold had a ball bearing in it effectivly blocking it off, should that be there ? i have also just replaced all the spark plugs the EGR seems to be working fine and i have vacuum in the line, i don't know what to try next , any ideas would be gratefully appreciated.

Gary

The entire purpose of the EGR valve is to stop pinging. Take the BB out of the line, set the timing at 12, and see what happens. If the spring inside the EGR valve is weak, you may get a hesitation. If so, you need a new valve, or you could put a delay in the line instead of the plug. Reach up under the valve at idle, and lift the diaphram. The engine should slow down and maybe stall. If not the passages are plugged.
They likely marked the timing at 8 with the EGR plugged to stop the pinging.

|UPDATED|7/10/2004 8:51:16 PM (AZT)|/UPDATED|

Ken

Thanks for the response, i will certainly try the 12 degrees again(but i am sure the 3 degrees would be better, remeber the band, oh shit showing my age)anyway back to the car, do you have any idea why someone would block off the EGR like that is it to get through inspection or something ?, i also noticed the old plug color was very light when i took them out so maybe the mixture is too weak, I have a Rochester carb but know noting about them so i shall have to check the book to see how to strengthen the mixture.

Gary

Many people think the EGR is always bad (and sometimes it can be), and just plug it becuase they can. If they use a very high octane fuel the EGR is not needed, so they might have plugged it for that reason. But with pump fuel, it may still be needed.

Fuel mix at idle can be riched up by backing out the mixture screws on the carb. Cruising mixture requires a jet or rod change. A slight tan color on the plugs is ideal.

Old song? Isn't that a newer group?

|UPDATED|7/11/2004 8:19:02 PM (AZT)|/UPDATED|

What about pinging anywhere from 1000 to 2000 rpm during acceleration? Does the previous info apply to a crossfire setup. Also, please explain the reason for pinging or piston knock? I have understood it to mean that, depending on the type of spark plug used, some stay hot enough to cause pre-mature ignition before the piston has reached the end of the stroke......bad situation. What are the corrections?

when your adjusting timing.. adjusting idle timing or initial timing isnt the only thing to check.. when your car pings like the timing is too far advanced at a certain rpm it is very likely that your timing ramp rate is too high.

on cars with stock distibutors usually means that your distributor springs are worn out.

nobody ever replaces these.. ive seen springs broken from rust, ive seen springs that were the same length off the distrutor as they are on the dist (ie no spring tension left)

initial timing is a very small part of the picture.. you must control your total timing at various rpm's with springs (of various strengths) and limit bushings (of various sizes.

you can have your timing locked in at an idle by vacuum optimization. and accelerate to 2000 rpm and the springs can be so loose that you instantly reach full timing and the engine cant handle it.

That pinging can also be from other sources than timing. EGR is one of them. Any hot spots in the cylinder can also cause the ping (knock). Too high of a heat range spark plug, running hot, carbon build up in the cylinder, can all cause the condition. So can too lean of a fuel mixture. Keep in mind, that is not just idle mix, you may need some jetting. Too low of an octane fuel will also cause ping.

Just be sure to completely check all systems. It would be a shame to retard timing to compensate for a lean fuel mix. You would lose power. But timing may be all you need, and maintain or even gain power.